290 lines
11 KiB
Java
290 lines
11 KiB
Java
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/*
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* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util;
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import java.util.function.Consumer;
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import java.util.function.DoubleConsumer;
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import java.util.function.IntConsumer;
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import java.util.function.LongConsumer;
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/**
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* A base type for primitive specializations of {@code Iterator}. Specialized
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* subtypes are provided for {@link OfInt int}, {@link OfLong long}, and
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* {@link OfDouble double} values.
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*
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* <p>The specialized subtype default implementations of {@link Iterator#next}
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* and {@link Iterator#forEachRemaining(java.util.function.Consumer)} box
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* primitive values to instances of their corresponding wrapper class. Such
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* boxing may offset any advantages gained when using the primitive
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* specializations. To avoid boxing, the corresponding primitive-based methods
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* should be used. For example, {@link PrimitiveIterator.OfInt#nextInt()} and
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* {@link PrimitiveIterator.OfInt#forEachRemaining(java.util.function.IntConsumer)}
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* should be used in preference to {@link PrimitiveIterator.OfInt#next()} and
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* {@link PrimitiveIterator.OfInt#forEachRemaining(java.util.function.Consumer)}.
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*
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* <p>Iteration of primitive values using boxing-based methods
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* {@link Iterator#next next()} and
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* {@link Iterator#forEachRemaining(java.util.function.Consumer) forEachRemaining()},
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* does not affect the order in which the values, transformed to boxed values,
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* are encountered.
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*
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* @implNote
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* If the boolean system property {@code org.openjdk.java.util.stream.tripwire}
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* is set to {@code true} then diagnostic warnings are reported if boxing of
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* primitive values occur when operating on primitive subtype specializations.
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*
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* @param <T> the type of elements returned by this PrimitiveIterator. The
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* type must be a wrapper type for a primitive type, such as
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* {@code Integer} for the primitive {@code int} type.
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* @param <T_CONS> the type of primitive consumer. The type must be a
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* primitive specialization of {@link java.util.function.Consumer} for
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* {@code T}, such as {@link java.util.function.IntConsumer} for
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* {@code Integer}.
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*
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* @since 1.8
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*/
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public interface PrimitiveIterator<T, T_CONS> extends Iterator<T> {
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/**
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* Performs the given action for each remaining element until all elements
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* have been processed or the action throws an exception. Actions are
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* performed in the order of iteration, if that order is specified.
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* Exceptions thrown by the action are relayed to the caller.
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* <p>
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* The behavior of an iterator is unspecified if the action modifies the
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* source of elements in any way (even by calling the {@link #remove remove}
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* method or other mutator methods of {@code Iterator} subtypes),
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* unless an overriding class has specified a concurrent modification policy.
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* <p>
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* Subsequent behavior of an iterator is unspecified if the action throws an
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* exception.
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*
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* @param action The action to be performed for each element
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* @throws NullPointerException if the specified action is null
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*/
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@SuppressWarnings("overloads")
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void forEachRemaining(T_CONS action);
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/**
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* An Iterator specialized for {@code int} values.
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* @since 1.8
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*/
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public static interface OfInt extends PrimitiveIterator<Integer, IntConsumer> {
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/**
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* Returns the next {@code int} element in the iteration.
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*
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* @return the next {@code int} element in the iteration
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* @throws NoSuchElementException if the iteration has no more elements
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*/
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int nextInt();
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/**
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* {@inheritDoc}
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* @implSpec
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* <p>The default implementation behaves as if:
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* <pre>{@code
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* while (hasNext())
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* action.accept(nextInt());
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* }</pre>
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*/
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default void forEachRemaining(IntConsumer action) {
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Objects.requireNonNull(action);
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while (hasNext())
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action.accept(nextInt());
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}
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/**
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* {@inheritDoc}
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* @implSpec
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* The default implementation boxes the result of calling
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* {@link #nextInt()}, and returns that boxed result.
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*/
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@Override
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default Integer next() {
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if (Tripwire.ENABLED)
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Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfInt.nextInt()");
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return nextInt();
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}
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/**
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* {@inheritDoc}
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* @implSpec
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* If the action is an instance of {@code IntConsumer} then it is cast
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* to {@code IntConsumer} and passed to {@link #forEachRemaining};
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* otherwise the action is adapted to an instance of
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* {@code IntConsumer}, by boxing the argument of {@code IntConsumer},
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* and then passed to {@link #forEachRemaining}.
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*/
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@Override
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default void forEachRemaining(Consumer<? super Integer> action) {
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if (action instanceof IntConsumer) {
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forEachRemaining((IntConsumer) action);
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}
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else {
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// The method reference action::accept is never null
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Objects.requireNonNull(action);
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if (Tripwire.ENABLED)
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Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfInt.forEachRemainingInt(action::accept)");
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forEachRemaining((IntConsumer) action::accept);
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}
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}
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}
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/**
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* An Iterator specialized for {@code long} values.
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* @since 1.8
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*/
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public static interface OfLong extends PrimitiveIterator<Long, LongConsumer> {
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/**
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* Returns the next {@code long} element in the iteration.
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*
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* @return the next {@code long} element in the iteration
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* @throws NoSuchElementException if the iteration has no more elements
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*/
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long nextLong();
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/**
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* {@inheritDoc}
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* @implSpec
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* <p>The default implementation behaves as if:
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* <pre>{@code
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* while (hasNext())
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* action.accept(nextLong());
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* }</pre>
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*/
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default void forEachRemaining(LongConsumer action) {
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Objects.requireNonNull(action);
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while (hasNext())
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action.accept(nextLong());
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}
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/**
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* {@inheritDoc}
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* @implSpec
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* The default implementation boxes the result of calling
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* {@link #nextLong()}, and returns that boxed result.
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*/
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@Override
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default Long next() {
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if (Tripwire.ENABLED)
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Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfLong.nextLong()");
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return nextLong();
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}
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/**
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* {@inheritDoc}
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* @implSpec
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* If the action is an instance of {@code LongConsumer} then it is cast
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* to {@code LongConsumer} and passed to {@link #forEachRemaining};
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* otherwise the action is adapted to an instance of
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* {@code LongConsumer}, by boxing the argument of {@code LongConsumer},
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* and then passed to {@link #forEachRemaining}.
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*/
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@Override
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default void forEachRemaining(Consumer<? super Long> action) {
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if (action instanceof LongConsumer) {
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forEachRemaining((LongConsumer) action);
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}
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else {
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// The method reference action::accept is never null
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Objects.requireNonNull(action);
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if (Tripwire.ENABLED)
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Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfLong.forEachRemainingLong(action::accept)");
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forEachRemaining((LongConsumer) action::accept);
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}
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}
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}
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/**
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* An Iterator specialized for {@code double} values.
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* @since 1.8
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*/
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public static interface OfDouble extends PrimitiveIterator<Double, DoubleConsumer> {
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/**
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* Returns the next {@code double} element in the iteration.
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*
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* @return the next {@code double} element in the iteration
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* @throws NoSuchElementException if the iteration has no more elements
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*/
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double nextDouble();
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/**
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* {@inheritDoc}
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* @implSpec
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* <p>The default implementation behaves as if:
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* <pre>{@code
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* while (hasNext())
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* action.accept(nextDouble());
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* }</pre>
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*/
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default void forEachRemaining(DoubleConsumer action) {
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Objects.requireNonNull(action);
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while (hasNext())
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action.accept(nextDouble());
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}
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/**
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* {@inheritDoc}
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* @implSpec
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* The default implementation boxes the result of calling
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* {@link #nextDouble()}, and returns that boxed result.
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*/
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@Override
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default Double next() {
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if (Tripwire.ENABLED)
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Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfDouble.nextLong()");
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return nextDouble();
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}
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/**
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* {@inheritDoc}
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* @implSpec
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* If the action is an instance of {@code DoubleConsumer} then it is
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* cast to {@code DoubleConsumer} and passed to
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* {@link #forEachRemaining}; otherwise the action is adapted to
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* an instance of {@code DoubleConsumer}, by boxing the argument of
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* {@code DoubleConsumer}, and then passed to
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* {@link #forEachRemaining}.
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*/
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@Override
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default void forEachRemaining(Consumer<? super Double> action) {
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if (action instanceof DoubleConsumer) {
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forEachRemaining((DoubleConsumer) action);
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}
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else {
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// The method reference action::accept is never null
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Objects.requireNonNull(action);
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if (Tripwire.ENABLED)
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Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfDouble.forEachRemainingDouble(action::accept)");
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forEachRemaining((DoubleConsumer) action::accept);
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}
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}
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}
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}
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